In a storage system provided with the non-volatile memory such as a flash memory, when writing is finished partway through a block at the time of power shutdown and the like, padding data is written to a subsequent page of a page to which data is written in order to fix the data of which writing is finished or to secure reliability of the data of which writing is finished. The reliability of the padding data itself may be low because writing to the subsequent page is not performed when the padding data is written.
In this type of storage system, the reliability of the data is improved by using an error correcting code. However, the inclusion of such padding data with low reliability into the data which configures the error correcting code may impair the correcting capabilities of the error correcting code.